In prior art gas pressure regulators, an attempt is made to construct them with as little friction as possible so as to achieve low hysteresis losses in operation. However, under low friction there exists a tendency for the moving parts to oscillate rapidly when gas flows through the inlet orifice. This produces an undesirable effect commonly called "buzz". One solution to this is to build mechanical friction into the pressure regulator to prevent the "buzz". The disadvantage of this solution however, is to produce increased hysteresis and associated losses.
Some prior art pressure regulators have approached the problem using a dash pot of partially filled liquid, which is orientation sensitive. Other prior art dash pots were complex and/or of limited use in that they were incorporated at the valve head.